1. Field of Invention
The present invention relates to a pigment surface treated with a particular N-acylamino acid derivative, especially with N-acylglycine hydroxyaluminum and/or N-acyl-N-methylglycine hydroxyaluminum, a highly concentrated solid pigment dispersion (high solid pigment dispersion) containing said surface treated pigment and a cosmetically acceptable oily material, and a cosmetic product (cosmetic composition) containing said pigment dispersion, and the like.
More specifically, the present invention provides a uniform highly concentrated solid pigment dispersion in a cosmetically acceptable oily material. Moreover, a cosmetic product made through the use of said pigment dispersion presents superior emulsion stability and exhibits moist (dewy) touch important for smooth feeling, superior adhesion to the skin, and long-lasting.
2. Related Art
When pigments, especially inorganic pigments, are used as colorants in cosmetic products, a uniform dispersion with a consistent color development and a good dispersion stability are required. However, pigments, especially inorganic pigments, such as titanium oxides (dioxides or the like) and iron oxides and the like, tend to aggregate due to their fine particle size and strong hydrophilic nature. Therefore, when the pigments are dispersed in the oily materials, the poor affinity of the pigments and oily materials leads to a high viscosity of the dispersions (mixtures of said pigments and said oily materials) and it is impossible to achieve a good dispersion even with an extended shear.
On the other hand, there have been many suggestions to make pigments lipophilic (oleophilic) (refer to Japanese Patent Kokai Publication JP-A-58-72512; U.S. Pat. No. 4,606,914, and Japanese Patent Kokai Publication JP-A-2000-7942.) so far. However, even though lipophilicity (oleophilicity) of the pigments is significantly improved according to the suggestions, easy dispersible pigments which can be well dispersed by brief low-shear in the oily materials are not disclosed in these suggestions.
For example, it has been reported that N-acylamino acid salt has a good affinity with pigments and oils (oily materials), and will improve dispersibility (dispersion capability) of the pigments in the oily materials significantly. Further, when makeup products contains pigments surface treated with such N-acylamino acid salt, pigment dispersibility of the makeup products is significantly improved (refer to Japanese Patent Kokai Publication JP-A-58-72512.). The pigments treated with the N-acylamino acid salt as reported have improved affinity with the oily materials; however, the improvement thereof is insufficient, especially dispersion of the pigments in oil phase in emulsion system of water-in-oil and oil-in-water is not satisfactory. Therefore, apparent micelle size becomes inconstant, and water-droplet, in case of the water-in-oil emulsion, and oil-droplet, in case of the oil-in-water emulsion, become irregular, resulting in unstable emulsion. On the other hand, pigments that can be well dispersed by brief low-shear in the oily materials are not disclosed in any reports.
Under these above circumstances, it is desirable to develop a pigment dispersion with an excellent dispersibility as compared with prior art; that is a pigment dispersion wherein the pigment particles (particles of the pigment) can be dispersed uniformly in the cosmetically acceptable oily material in brief time (at a shorter time), and also a stable, uniform high solid dispersion of pigments (pigment particles) in the cosmetically acceptable oily material wherein the pigment particles can be uniformly dispersed in oil phase of emulsion in brief time; and a cosmetic product (cosmetic composition) with an excellent emulsion stability containing such pigment dispersion.
Problem to be Solved by Invention
It is an object of the present invention or a problem to be solved by the invention to provide a pigment dispersion for use in cosmetics (cosmetic products) with an improved dispersion stability and versatility (ease of dispersion and wide rage of usage) compared to the existing technology, and a cosmetic product (cosmetic composition) with an excellent emulsion stability and improved usage and feel (smooth feeling) compared to the existing cosmetic products.
The present inventors have discovered, during a study to solve the previous problem, that pigments (pigment particles) surface treated with N-acylglycine hydroxyaluminum and/or N-acyl-N-methylglycine hydroxyaluminum are easily and uniformly dispersed in short period of time in cosmetically acceptable oily material, and that the pigment dispersion containing these pigments (pigment particles) and the cosmetically acceptable oily material will provide with an excellent dispersion stability and versatility (ease of dispersion and wide rage of usage) because of the ability of these pigments (pigment particles) to be uniformly dispersed at a high concentration in the cosmetically acceptable oily material. Further, it has been also discovered that a cosmetic product (cosmetic composition) which contains these surface treated pigments (pigment particles) or the pigment dispersion containing these surface treated pigments, has uniform and stable micelles, especially in water-in-oil and oil-in-water emulsions, and is stable as an emulsion and has a better usage than the existing products because the pigments (pigment particles) are not only very lipophilic (good affinity with the oily materials) and very but also uniformly dispersed in the oily materials. The above variety of knowledge has led to the completion of the present invention.
That is, the present invention lies in a surface treated pigment (referred to as the surface treated pigment of the present invention) for a cosmetic product, wherein the surface of the pigment particles is coated with N-acylglycine hydroxyaluminum and/or N-acyl-N-methylglycine hydroxyaluminum (referred to as the surface treatment agent(s) used in the present invention). In other words, the present invention lies in a surface treated pigment for a cosmetic product comprising particles (pigment particles) the surface of which is coated with N-acylglycine hydroxyaluminum and/or N-acyl-N-methylglycine hydroxyaluminum.
Furthermore, the N-acyl groups of said N-acylglycine hydroxyaluminum and said N-acyl-N-methylglycine hydroxyaluminum are independent from each other, and each may be selected from a N-myristoyl group, a N-lauroyl group, a N-palmitoyl group, and a N-stearoyl group, preferably a N-myristoyl group to provide a surface treated pigment with a better dispersibility. According to the present invention, a pigment to be treated (pigment before surface treatment, pigment used for production of the surface treated pigment), if selected from titanium oxides and iron oxides, such as TiO2, FeOxc2x7OH, Fe2O3 and Fe3O4, may be rendered with superior dispersibility by surface treatment.
The present invention also lies in, as an another form, a pigment dispersion comprising the surface treated pigment described above, the surface of which (the surface of the pigment particles) is coated with the N-acylglycine hydroxyaluminum and/or the N-acyl-N-methylglycine hydroxyaluminum, and a cosmetically acceptable oily material.
The pigment dispersion of the present invention, when the said cosmetically acceptable oily material (oil solution) is selected from silicone fluids (oils) and fatty acid esters (fatty acid ester oils or the like), delivers an excellent dispersion due to ease of dispersing pigments (pigment particles). Moreover, the pigment dispersion of the present invention has an excellent fluidity (liquidity) because surface treated pigments (pigment particles) are uniformly and stably dispersed in the cosmetically acceptable oily material. Pigment dispersions with viscosity preferably equal to or less than 100,000 mPa.sec (at highest 100,000 mPa.sec, not more than 100,000 mPa.sec), more preferably from about (approxymately) 100,000 to about 500 mPa.sec, most preferably from about 5,000 to about 1,000 mPa.sec may be provided according to the present invention.
The present invention lies in, as an another form, a cosmetic product (referred to as a cosmetic product of the present invention) comprising said surface treated pigment(s) or said pigment dispersion(s).
Besides, it is especially preferable to use the cosmetic product of the present invention as a liquid foundation, a lip gloss, an eyeliner, a mascara, a cream eye-shadow, a tinted moisturizer, or a sunscreen product.